Dust seal for sliding type bush

ABSTRACT

A dust seal for a sliding type bush is interposed between a stationary section and a movable section. The dust seal has a fitting portion fitted to the stationary section, a seal lip portion in sliding contact with the outer circumferential surface of the movable section and a flexible portion interconnecting the fitting portion and the seal lip portion. The dust seal is further provided with an annular projection held in contact with a flange and the outer circumferential surface of the movable section. The seal lip portion is held axially stationarily relative to the movable section.

This application is a continuation of application Ser. No. 07/304,078,filed Jan. 31, 1989 now abandoned.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates in general to bushes used for connecting asuspension or the like to a vehicle body and more particularly to a dustseal for a sliding type bush for use in an automotive vehicle or thelike.

II. Description of the Prior Art

A sliding type bush has a stationary section fixed to a vehicle body orthe like, an axially movable or slidable section and a dust sealinterposed between the stationary and movable sections for preventingingress of dust, water, etc. into the bush.

The prior art sliding type bush has a disadvantage that its dust seal isliable to be damaged within a short period of usage, i.e., cannotfunction desiredly over a long period of usage. This is because theouter surface portion of the movable section located outside of the dustseal is exposed to the open air, mud, water, etc. and therefore has apossibility of rusting, resulting in axial movement of the movablesection which causes the seal lip portion of the dust seal to slide onthe rusted surface portion and be damaged thereby.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an improveddust seal for a sliding type bush which comprises a stationary sectionand a movable section disposed concentrically with the stationarysection and movable relative to the stationary section. The movablesection has a flange for limiting axial movement thereof.

The bush further comprises a dust seal interposed between the stationarysection and the movable section for providing a seal therebetween.

The dust seal has a fitting portion fitted to the stationary section, aseal lip portion in sliding contact with an outer circumferentialsurface of the movable section and a flexible portion disposed betweenthe fitting portion and the seal lip portion.

The dust seal further has at the joint beween the flexible portion andthe seal lip portion an annular projection held in contact with theflange and the outer circumferential surface of the movable section.

This structure is effective for solving the above noted problems.

It is accordingly an object of the present invention to provide animproved dust seal for a sliding type bush which can function properlyor desiredly over a long period of usage.

It is a further object of the present invention to provide an improveddust seal of the above described character which can effect an improvedsealing action.

It is a further object of the present invention to provide an improveddust seal of the above described character which can function assuredlyeven when wear of the dust seal occurs to some extent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view similar to FIG. 3 but showing a dust seal for a slidingtype bush according to an embodiment, of the present invention;

FIG. 2 is a sectional view of a sliding type bush which has beenproposed by Japanese patent application 62-70496 which is not a priorart but a so-called internal prior art; and

FIG. 3 is a fragmentary enlarged sectional view of a dust seal and itsadjacent parts utilized in the sliding type bush of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 2 and 3, description is first made to a sliding typebush 20 proposed by Japanese patent application 62-70496 which, however,is not a prior art but a so-called internal prior art, in order tofacilitate understanding of this invention.

The sliding type bush 20 is shown as comprising an annular stationarysection 1, annular movable section 2 concentric with the stationarysection 1 and an annular dust seal 3 interposed between the stationarysection 1 and the movable section 2. The movable section 2 is axiallymovable or slidable relative to the stationary section 1 thoughlimitedly. The dust seal 3 is located at an outer end of the dust.

Though not shown, another structural portion identical with what isshown in FIG. 2 is in effect disposed symmetrically with respect to theaxis "C" so that two dust seals 3 are located on the opposite axial endsof the bush 20.

The stationary section 1 consists of four concentric tublar members,i.e., an outer tube 4, an annular lining 5, an intermediate tube 6 andan annular elastic member 7. The lining 5 is fitted in the intermediatetube 6. The movable section 2 is received in or passes through thelining 5 in such a way as to be slidable on the inner circumferentialsurface of the lining 5. The outer tube 4 is disposed around theintermediate tube 6 and the lining 5. The elastic member 7 is interposedbetween the outer tube 4 and the intermediate tube 6 to absorb shocksapplied thereto. The intermediate tube 6 is stepped to have and outwardflange 6a and an enlarged diameter otter end portion 6b at the outer endof the flange 6b. The outer tube 4 and the lining 5 have at the outerends thereof outward flanges 4a and 5a which are located on the oppositesides of the flange 6a. The elastic member 7 has at an outer end thereofan outward flange 7a interposed between the flanges 4a and 5a of theouter tube 4 and the lining 5.

The movable section 2 consists of an inner tube 8 for attaching the bush20 to a suspension (not shown) or the like by way of a mounting bracket,bolts, etc. The inner tube 8 has adjacent to an end thereof an outwardflange 8a which is recieved within the enlarged diameter outer endportion 6b of the intermediate tube 6 and operative to abut upon theoutward flange 5a of the lining 5 to limit axial movement of the innertube relative to the movable section 1.

Apart from the above description, connections may oppositely be made sothat the outer tube 4 side serves as a movable section and the innertube 8 side serves as a stationary section.

The dust seal 3 has a fitting portion 9 fitted in the stationary section1, a seal lip portion 10 in sliding contact with the movable section 2and a flexible portion 11 operative to allow relative movement(i.e.,relative axial movement, relative radial movement or oscilationand relative rotation) between the stationary section 1 and movablesection 2.

With the above described construction and arrangement, the dust seal 3is operative to prevent ingress of dust, mud, water, etc. into the bushand egress of grease for the grease clearance A, B out of the bush 20while allowing relative movement between the stationary section 1 andthe movable section 2.

In the sliding type bush 20, the outer circumferential surface portionof the inner tube 8 located outside of the seal lip portion 10 isexposed to the open air, mud, water, etc. and has a possibility of beingcovered with rust "R". Since the seal lip portion 10 is axially movableor slidable relative to the inner tube 8, axial movement of the innertube 8 by the grease clearace "A" causes the edge 10a of the seal lipportion 10 to slide on the inner tube 8 axially thereof and ride on orengage the rusted surface portion, thus causing the seal lip portion 10to be damaged, i.e., wear out rapidly and therefore making it impossiblefor the dust seal 3 to function properly or desiredly over a long periodof usage.

This invention aims at solving the above problems.

Referring to FIG. 1 in which like or corresponding parts and portions tothose of the bush 20 in FIGS. 2 and 3 are designated by the samecharacters, a dust seal 3' for a sliding type bush 20' according to anembodiment of this invention includes a one-piece annular main body 23made of rubber. The main body 23 includes a fitting portion 9 fitted inthe stationary section 1, a seal lip portion 10 in sliding contact withthe movable section 2 and a flexible portion 11 for allowing relativemovement between the stationary section 1 and the movable section 2.

The dust seal 3' further includes an outer peripheral ring 12 embeddedin the fitting portion 9 in such a way as to extend parallely along theouter periphery of the fitting portion 9 so that the fitting portion 9is urged by the peripheral ring 12 against the inner circumferentialsurface of the enlarged diameter outer end portion 6b of theintermediate tube 6 and thereby fixed to the intermediate tube 6.

The flexible portion 11 extends radially and axially inwardly from anouter axial end of the fitting portion 9 and is merged at the innerperipheral end into the seal lip portion 10 so as to allow relativemovement between the stationary section 1 and the movable section 2. Theseal lip portion 10 is axially waved to have three sealing edges 10a incontact with the outer periphery of the inner tube 8 to effect a sealingaction. The dust seal 3' further includes a garter spring 13 fitted inthe seal portion 10 so that the sealing edges 10a are urged by thegarter spring 13 against the outer circumferential surface of the innertube 8.

The main body 23 further has an annular projection 15 at the joint 14between the flexible portion 11 and the seal lip portion 10. The annularprojection 15 projects axially and radially inwardly of the bush 23 tohave an annular free end urged and held in contact with the joint 16between the flange 8a and the outer circumferential surface of the innertube 8, i.e., the annular rubber projection 15 is so designed as to beheld at the free end in contact with the flange 8a under the bias of theflexible portion 23 even if the inner tube 8 constituting the movablesection 2 moves relative to the dust seal 3 by the grease clearance "A"in the axial direction thereof.

From the foregoing, it will be understood that axial movment of theinner tube 8 by the grease clearance "A" causes the seal lip portion 10to move correspondingly, thus allowing the sealing edges 10a to contactthe outer circumferential surface of the inner tube 8 at axiallystationary positions thereof, i.e., the sealing edges 10a moves with theinner tube 8 while being held axially stationarily relative to the outercircumferential surface of the inner tube 8. By this, it becomespossible to prevent the sealing edges 10a from riding on or engaging theouter circumferential portion of the inner tube 8 which is exposed tothe open air, mud, water, etc. and covered with rust "R" and thereforeit becomes possible to prevent the sealing edges 10a from being damagedby the rusted outer circumferential portion.

It will be further understood that since the projection 15 is adapted tocontact not only the flange 8a but the outer circumferential surface ofthe inner tube 8, it becomes possible to hold the annular projection 15in good contact with the inner tube 8 even when axial movement of theinner tube 8 occurs.

It will be further understood that the annular projection 15 iseffective for maintaining the seal lip portion 10 in a good posturerelative to the inner tube 8, i.e., effective for maintaining therelative positions of the seal lip portion 10 and the outercircumferential surface of the inner tube 8 substantially unchangedthereby maintaining a good sealing function even when axial movement ofthe sealing lip portion 10 becomes large due to the grease clearance"B".

It will be further understood that even when wear of projection 15occurs, the sealing lip portin 10 is caused to move toward the flange8a, i.e., toward the outer circumferential surface portion of the innertube 8 which is not rusted, thus making it possible to preventaccelerated wear of the seal lip portion 10 due to wear of the annularprojection 15 and therefore making it possible to maintain the desiredsealing function of the dust seal over a long period of usage.

What is claimed is:
 1. A sliding type bush comprising:concentric innerand outer sections movable relative to each other; and a dust seal forproviding a seal between said inner and outer sections; said innersection having a flange abuttingly engageable with said outer sectionfor limiting movement of said inner section relative to said outersection; said dust seal having a fitting portion fitted in said outersection, an annular seal lip portion in sliding contact with an outercircumferential surface of said inner section and an annular flexibleportion interconnecting said fitting portion and said seal lip portion;said dust seal further having on an inner side thereof and at a junctionbetween said flexible portion and said seal lip portion an annularprojection for contact with said flange and said outer circumferentialsurface of said inner section; and said fitting portion having an outerend located more remotely from said flange than an inner end, and saidseal lip portion having an inner end located nearer to said flange thanan outer end, said flexible portion extending curvedly between saidouter end of said fitting portion and said inner end of said seal lipportion for allowing axial movement of said inner section relative tosaid outer section while holding said annular projection in contact withsaid flange and said outer circumferential surface of said inner sectionunder a bias of said flexible portion.
 2. The sliding type bushaccording to claim 1 further comprising a garter spring placed aroundsaid seal lip portion for urging said seal lip portion against saidouter circumferential surface of said inner section.
 3. The sliding typebush according to claim 2 wherein said seal lip portion has an innercircumferential surface which is waved to form a plurality of sealingedges which are held axially stationary relative to said outercircumferential surface of said movable section.
 4. The sliding typebush according to claim 3 further comprising an outer peripheral ringembedded in said fitting portion for urging said fitting portion againstsaid stationary section.
 5. The sliding bush according to claim 1,wherein said flexible portion is generally "S" shaped.
 6. A sliding typebush comprising:an outer stationary section; an inner movable sectiondisposed concentrically with said stationary section and movablerelative to said stationary section; a dust seal for providing a sealbetween said stationary and movable sections; means for limiting axialmovement of said movable section relative to said stationary section,said axial movement limiting means including a radially outwardextending flange of said movable section and a radially inward extendingflange of said stationary section for abutment upon each other; saiddust seal having a fitting portion fitted in said stationary section, anannular seal lip portion in sliding contact with an outercircumferential surface of said movable section and an annular flexibleportion interconnecting said fitting portion and said seal lip portion;said dust seal further having at a junction between said flexibleportion and said seal lip portion an annular projection for contact withsaid radially outward extending flange and said outer circumferentialsurface of said movable section; and said fitting portion having anouter end located more remotedly from said radially outward extendingflange than an inner end, and said seal lip portion having an inner endlocated nearer to said flange than an outer end, said flexible portionextending curvedly between said outer end of said fitting portion andsaid inner end of said seal lip portion for allowing axial movement ofsaid movable section relative to said stationary section while holdingsaid annular projection in contact with said radially outward extendingflange and said outer circumferential surface of said movable sectionunder a bias of said flexible portion.
 7. A sliding type bushcomprising:an outer stationary section; an inner movable sectiondisposed concentrically with said stationary section and movablerelative to said stationary section; a dust seal for providing a sealbetween said stationary and movable sections; means for limiting axialmovement of said movable section relative to said stationary section,said axial movement limiting means including a radially outwardextending flange of said movable section and a radially inward extendingflange of said stationary section for abutment upon each other; saiddust seal having an annular fitting portion fitted in said stationarysection, an annular seal lip portion in sliding contact with an outercircumferential surface of said movable section and an annular flexibleportion interconnecting said fitting portion and said seal lip portion;said dust seal further having at a junction between said flexibleportion and said lip portion an annular projection for contact with saidradially outward extending flange and said outer circumferential surfaceof said movable section; said fitting portion having an outer endlocated more remote from said radially outward extending flange than aninner end, and said seal lip portion having an inner end located nearerto said radially outward extending flange than an outer end, saidflexible portion extending curvedly between said outer end of saidfitting portion and said inner end of said seal lip portion for allowingaxial movement of said movable section relative to said stationarysection while holding said annular projection in contact with saidradially outward extending flange and said outer circumferential surfaceof said movable section under a bias of said flexible portion; and saiddust seal further having an outer peripheral ring for fixing saidfitting portion to said stationary section, said outer peripheral ringaxially extending generally in parallel to an inner periphery of saidfitting portion to have opposite axial ends, one of which terminates ata junction between said outer end of said fitting portion and saidflexible portion, and the other of which terminates at said inner end ofsaid fitting portion.